H74: Ensuring that opening and closing tags are used according to specification

Applicability

Description

The objective of this technique is to avoid key errors that are known to cause
problems for assistive technologies when they are trying to parse content which involve
having opening and closing tags that are not used according to specification. These
errors can be avoided by using the HTML or XHTML mechanism to specify the technology and
technology version, and making sure the Web page does not have these types of errors in
it. There are several validators that the developer can use: validation reports
generally mention these types of errors. This technique deals only with errors related
to incorrectly formed opening and closing tags. The document type declaration is not
strictly necessary for this type of evaluation, but specifying the document type
declaration makes it easier to use a validator.

Examples

Example 1: HTML

HTML pages include a document type declaration (sometimes referred to as
!DOCTYPE statement). The developer can use offline or online
validators (see Resources below) to check that all id attribute values are unique
and that opening and closing tags are used according to the specification.

Example 2: XHTML

Like other other XML-based documents, XHTML documents reference a Document Type
Definition (DTD) or other type of XML schema. The developer can use online or
offline validators (including validation tools built into editors) to check that
opening and closing tags are used according to the specification.

Example 3: Using test frameworks

When a Website generates HTML or XHTML dynamically instead of serving only static pages, a
developer can use XHTMLUnit,
XML Test Suite or a similar
framework to test the generated XHTML code.

Related Techniques

Tests

Procedure

Check that there are closing tags for all elements with required closing tags.

Check that there are no closing tags for all elements where closing tags are
forbidden.

Check that opening and closing tags for all elements are correctly nested.

Expected Results

Steps 1, 2, and 3 are true.

If this is a sufficient technique for a success criterion, failing this test procedure does not necessarily mean that the success criterion has not been satisfied in some other way, only that this technique has not been successfully implemented and can not be used to claim conformance.